Investigating the Root Causes of Alite (C₃S) Variation in Clinker Production: A Case Study of a Northern European Cement Plant

Sammanfattning

This thesis investigates the variability of tricalcium silicate (alite, C₃S) content in clinker production at a Northern European cement plant, through statistical analysis, guided by cause-and-effect philosophies and TQM theory. A five-year dataset (2020–2025) of automatic clinker samples was analysed using descriptive statistics, regression modelling, factorial plots, and variance-inflation diagnostics implemented using Excel and Minitab. The analysis found that variability in Al₂O₃ content is the primary cause of alite variation (R² = 0.90), whereas other oxides exhibited weaker relationships that were difficult to interpret with a simplistic approach. Root cause analysis was applied to reframe statistical findings into process improvement strategies.Based on these insights, a control loop proposal for real-time monitoring of raw meal composition is presented to stabilise slag input and reduce clinker variability. Contributions include quantification of root causes in an industrial engineering context, demonstration of root cause analysis applied in continuous process systems, and a pragmatic control loop design for clinker quality enhancement. Future work could explore advanced multivariate control, experimentation, advanced stoichiometric and thermodynamic modelling, and rerouting to XRF-feedback for further stabilisation of alite variability.